Merge pull request #7476 from tchaikov/wip-include-expat-in-source

rgw: do not include "expat.h" in header file

Reviewed-by: Sage Weil <sage@redhat.com>

diff --cc src/rgw/rgw_acl_s3.h
Simple merge

diff --cc src/rgw/rgw_xml.h
Simple merge